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Reading beyond the peaks: Optical analysis decodes spectral complexity in twisted semiconductor layers

A study from the Research Center for Materials Nanoarchitectonics (MANA), one of the centers under the National Institute for Materials Science (NIMS), presents a new method to reveal hidden material disorder reflected in complex photoluminescence spectra, paving the way for new optical diagnostics of material disorder in two-dimensional semiconductors and related light-emitting materials.

When two ultrathin semiconductor layers, such as molybdenum diselenide and tungsten diselenide (MoSe2/WSe2), are stacked with a slight twist, they form a repeating pattern called a moiré heterostructure. These structures have unusual light-emitting properties, featuring a complex landscape of photoluminescence spectra across their surface.

While scientists often analyze materials by looking at the individual peaks of their emission spectra, moiré heterostructures produce spectra with many overlapping peaks whose origins are difficult to explain individually.

New chip-based frequency combs demonstrate potential for portable atomic clocks

The world would look radically different without rulers and measuring tapes that fit into a pocket. Carpenters, fashion designers and engineers rely on these trusty tools to check the size of everything from a wooden board to a fabric swatch. But physicists who work with light lack that same convenience for one of the basic measurements of their craft. They routinely need to measure and compare the frequencies—colors—of the light waves they are using.

To date, they have lacked a similarly pocket-sized tool for routine measurements, and they make do with cumbersome equipment that crowds their lab space and is far from portable.

The standard tool for measuring the frequency of light is called an optical frequency comb. This device produces a rainbow of different frequencies of light, all spaced at regular intervals like the tick marks on a measuring tape. Frequency combs let researchers measure the difference between distinct frequencies and are crucial for many experiments and measurements that use light.

Chernobyl particles reveal unexpectedly stable nuclear fuel after 40 years

Four decades after the 1986 nuclear disaster, researchers at Leibniz University Hannover and the Helmholtz-Zentrum Dresden-Rossendorf (HZDR) examined six tiny, highly radioactive fragments that were released from the destroyed reactor in Ukraine in the wake of the incident. Analyses show that these “hot particles” are far more stable than had previously been assumed. The findings could allow for more precise assessments of the health risks posed by such radioactive particles. The paper is published in the Journal of Hazardous Materials.

The explosions hurled massive amounts of debris from the nuclear reactor, radioactive dust particles still contaminate the soil around the disaster area, known today as Chernobyl. Measuring only 8 to 50 micrometers, they remain highly radioactive even after 40 years. Even today, people may enter the affected areas only while wearing protective suits.

“There are three classes of these particles,” explains Tobias Weissenborn, a physicist and doctoral candidate at Leibniz University Hannover. “First, there are particles that are chemically and physically still very similar to the nuclear fuel uranium dioxide. Then, there are particles that are partially or fully encased in, or completely fused with, their zirconium layer.”

Stretching boosts thermal and electrical conductivity in new nanocomposite

A joint research team led by professors Seunghyun Baik and Joonmyung Choi from the School of Mechanical Engineering at Sungkyunkwan University (SKKU) has developed a new nanocomposite material whose electrical and thermal conductivities increase as it is stretched. The team successfully applied it to stable heat dissipation for foldable phones.

The research is published in Advanced Functional Materials.

Smartphones and electronic devices generate significant heat during operation, which can cause performance throttling or shorten device lifespan if not properly cooled. Next-generation flexible electronics that bend or stretch face particular challenges because heat cannot easily escape during deformation. Typically, stretching a material increases the distance between embedded particles, which reduces both thermal and electrical conduction. However, the research team designed a material that overturns this conventional understanding.

Blue-light labeling uncovers unexpected protein partners of folded DNA structures

DNA can be more than just a double helix. When four strands are folded into a compact bundle, they form a G-quadruplex (G4). These bundles form in guanine-rich regions across the genome, including telomeres at the ends of chromosomes and the control regions of genes, where the proteins that dock onto them help decide which genes are switched on. G4 does not act the same way everywhere. What it does depends on where it forms and which proteins bind to it. This is why understanding the interactions surrounding G4 is so important.

Biochemical assays give us more information about the intricacies of these interactions. These assays assess how DNA and proteins interact during processes such as DNA replication, transcription and repair. However, previous assays haven’t been able to capture the full picture.

A team led by Kazumitsu Onizuka and Shinichi Sato of Tohoku University, with Takanori Oyoshi of Shizuoka University, has developed a photocatalytic proximity labeling method that overcomes previous pitfalls and captures partners that earlier methods missed. The technique also revealed hexokinase-1 to be an unexpected player in these interactions.

A 2-in-1 approach captures toxic metals and recovers rare earth elements from wastewater

We generally throw away a broken camera lens, earphones or an old phone that has stopped working and is beyond repair because they seem useless when they no longer function. However, these objects contain rare earth elements (REEs) that have applications in magnets, superconductivity, optics and batteries, among others. When these objects end up in water, recovering REEs becomes difficult.

Industrial activities can also introduce toxic metals such as lead, cadmium, nickel and manganese into the same water. The challenge is no longer simply how to remove these unwanted, harmful metal pollutants from water, but also how to efficiently recover the valuable REEs.

What if a single strategy could help address both issues? To that end, researchers from the Indian Institute of Technology Gandhinagar (IITGN), the University of Cambridge and the University of Birmingham have developed a protocol using a class of highly porous materials called metal-organic frameworks (MOFs). These materials can efficiently capture toxic metals from water as well as recover valuable REEs from waste streams.

Wave-shaped wall and roof designs can protect against hurricane-force winds

Florida State University faculty are helping build stronger structures by examining how wave-shaped patterns on exterior walls and roofs reduce wind loads on low-rise buildings by up to 60%.

The research, which was published in Engineering Structures, could help architects and engineers combat hurricane-force winds through innovative building shapes.

“Changing a building’s shape can significantly reduce the intensity of wind forces it has to withstand,” said Pedro Fernández-Cabán, one of the co-authors of the work and an assistant professor of civil engineering at the FAMU-FSU College of Engineering. “These nonconventional building shapes reduce the damage from worst-case severe weather scenarios. It’s another tool for engineers and designers to protect against wind damage.”

Blocking a nerve protein could interrupt chronic pain rather than simply mask it

Chronic pain can continue long after an initial injury. When a nerve outside the brain and spinal cord (a peripheral nerve) is damaged and does not heal properly, it keeps sending constant pain signals. Over time, this nonstop bombardment of pain signals changes how your spinal cord and brain process information as sensory and emotion-associated circuits become hyperreactive, turning up the volume on pain.

Current pain treatments do not work well for everyone and can cause significant side effects. Painkillers like morphine just hide the pain, but researchers at Boston University Chobanian & Avedisian School of Medicine have identified the underlying problem.

X-ray technique reveals how quantum materials respond to laser pulses in real time

Creating a quantum device often begins by intentionally damaging a crystal. Scientists fire an ultrafast laser pulse into a material, knocking atoms out of place and leaving behind tiny imperfections called vacancies. Far from being flaws, these vacancies can behave as qubits—the fundamental building blocks of quantum information.

The challenge is precision.

Researchers want to place these quantum defects exactly where they need them, but until now they have had only a limited understanding of what happens inside a crystal during the instant when a laser creates the defect.

Can a passing black hole disturbance leave a trace in Hawking radiation?

Black holes, despite their extreme nature, are described by surprisingly few basic parameters: their mass, charge and spin. Two black holes may have formed for completely different reasons and passed through very different histories, yet still end up in the same final state. John Wheeler summarized this idea with the famous phrase “black holes have no hair.”

Once quantum physics enters the picture, things become more complicated. As Stephen Hawking showed in the 1970s, black holes have a temperature and produce what we now call Hawking radiation. For a stationary black hole, this radiation has a characteristic temperature related to the surface gravity.

The real universe is much less ideal. Finding a completely isolated black hole is not easy. Matter may fall toward it, a nearby companion may disturb the surrounding spacetime, or external fields may change. For some period of time, the black hole can therefore be away from its quiet stationary state.

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